The long-term objective of this project is to fully define the constituents of the int-1 proto-oncogene family and to begin to elucidate the role that these genes play in tumorigenesis and embryonic development. This family currently consists of a small group of 3 secreted factors, related by amino acid sequence, that have oncogenic potential and additionally appear to function during development. Preliminary data indicate, however, that at least 7 other int-1 related genes exist. It is anticipated that these and other newly identified genes of this family will possess many of the qualities of the known members (e.g., oncogenic and developmental functions, growth factor-like structure and activity). Specifically, the long term objective will be approached by first isolating all novel members of the murine int-1 proto-oncogene family followed by characterization of these genes in terms of their expression patterns and possible involvement in tumorigenesis, as the following describes: 1) The polymerase chain reaction will be used to amplify DNA from genes in the int-1 family using DNA primers corresponding to conserved regions in the 3 presently known members. Amplified fragments determined to be novel (and int-1 related) by sequence analysis will be used as probes to isolate cDNA clones. 2) The normal expression patterns of these new genes, in adult mice and embryos, will be characterized by Northern blotting and in situ hybridization in order to gain clues as to their individual functions. 3) Transforming activities of these genes will be tested in appropriate cells in culture after gene transfer by transfection or retrovirus infection. Cells receiving these genes will be assayed for tumorigenicity in syngeneic or athymic nude mice. 4) After isolating specific human DNA probes for each of these new genes, a broad survey of human tumors and tumor cell lines will be conducted for evidence of involvement of each gene; rearrangement, amplification, and expression of each gene will be tested.